The present invention generally relates to intravascular devices and methods of use. In particular, the present invention relates to intravascular occlusion balloon catheters and their use to prevent migration of embolic materials during an intravascular procedure.
Minimally invasive intravascular procedures are common in the treatment of vascular disease. For example, intravascular restrictions due to atherosclerosis, restenosis, or the like may be dilated by intravascular balloon catheters or may be removed by intravascular atherectomy catheters. These intravascular procedures and the use of their associated devices may result in embolic particles being dislodged as the restriction is being dilated or cut. The embolic particles may cause an embolism to form downstream of the restriction which, in turn, may compromise the flow of blood to the surrounding tissue.
To alleviate this potential risk, intravascular occlusion balloon catheters have been developed. Such occlusion catheters typically include an elongate shaft and a distally mounted balloon. The shaft and the balloon are insertable into a lumen of a primary catheter such as a dilatation catheter or an atherectomy catheter. The occlusion balloon is positioned distal of the treatment site and temporarily inflated to prevent embolic particles from flowing downstream as the restriction is being dilated or cut. After the restriction has been treated, the primary catheter is removed over the occlusion balloon catheter. The treatment site proximal of the occlusion balloon is then aspirated through a guide catheter. Once the embolic particles have been aspirated, the occlusion balloon is deflated and removed from the patient.
In order to retract the primary catheter over the occlusion balloon catheter, the occlusion catheter must be approximately two times the length of the guidewire lumen of the primary catheter. Dilatation catheters are typically 70-150 cm in length, which requires the occlusion catheter to be approximately 140-300 cm or more in length. An occlusion catheter of such length may compromise the ability of the treating physician to manipulate the catheter and is otherwise cumbersome to handle. Accordingly, it is desirable to provide a relatively short intravascular occlusion balloon adapted for use with a standard length primary catheter. It is also desirable to provide an occlusion catheter that is simple to prepare for use.
The present invention provides an intravascular occlusion balloon catheter having a length slightly greater than a conventional balloon or atherectomy catheter. The intravascular occlusion balloon catheter includes, in preferred embodiments, a removable hub, a profile sized to approximate a guidewire, and a means for venting air from the balloon. The removable hub and the small profile allow the occlusion balloon catheter to be used as a standard length guidewire. The venting means allows air to be easily and reliably removed from the balloon prior to use.
The venting means may comprise an annular ring disposed about the distal end of the shaft with an intermediate tube fixedly connected to the balloon and movably disposed about the annular ring. The intermediate tube and the annular ring form a fluid tight seal to permit inflation and deflation of the balloon. The intermediate tube includes a vent hole, wherein a vent path is opened through the tube and the vent hole when the hole is positioned distal of the annular ring. The vent path may be closed to inflate the balloon by positioning the hole proximal of the annular ring.
In one alternative embodiment, a pair of longitudinally spaced annular rings are included proximate the distal end of the shaft with at least one hole penetrating through the shaft between the annular rings. The shaft extends distally from the more distal annular ring and the balloon is sealingly affixed at the distal end thereof. An intermediate tube is slidably mounted relative to the longitudinally spaced annular rings such that in a first position or proximal position, the vent hole is opened through the tube and a vent path is created to the exterior of the catheter for purging the catheter. In a second position or distal position, the intermediate tube extends over both the proximal and distal annular rings in sealing engagement to block the vent hole to allow inflation of the balloon during use.
Alternatively, the venting means may comprise an intermediate tube disposed between the balloon and the distal end of the shaft. The tube includes an inflation lumen, a vent lumen, and a vent hole, with a movable plug disposed in the vent lumen. A vent path is opened through the vent lumen and the vent hole when the plug is positioned proximal of the hole. The vent path may be closed to inflate the balloon by positioning the plug distal of the hole. A retainer may be disposed in the vent lumen distal of the vent hole to prevent the plug from entering the balloon. In this embodiment, a pusher is used to move the plug from a venting configuration to an inflation configuration. The catheter shaft may include an access port proximal of the movable plug so that the pusher may be inserted through such port. This design eliminates the need for the pusher to extend through the inflation lumen of the shaft. However, an alternative design includes the pusher extending within the inflation lumen to the movable plug.
The venting means may also comprise a re-sealable material disposed in a lumen of an intermediate tube disposed between the balloon and the distal end of the shaft. A vent path is opened when a needle is disposed through the re-sealable material. The vent path may be closed to inflate the balloon by removing the needle from the re-sealable material.
The venting means may also comprise a vent lumen extending between the balloon interior and a vent hole. A coaxially disposed intermediate tube or sleeve may be slidably disposed over the catheter shaft in a first position to allow venting through the vent hole. The slidably disposed sleeve may be moved to a second, sealed, position for occluding the vent hole to allow inflation of the balloon.
The venting means may also comprise a vent lumen extending between the balloon interior and the vent hole together with a plug dimensioned for insertion into the vent lumen. The catheter can be purged through the vent lumen, followed by plugging the vent lumen by inserting the plug. The plug may be radiopaque and may comprise a swellable polymer injected into the vent lumen.
The venting means may also comprise a vent lumen extending between the balloon interior, a vent hole, and a proximally disposed plug access hole vent. A plug may be slidably disposed in the vent lumen in a first position proximal of the vent hole for purging the balloon. The plug may be moved into a second position for occluding the vent hole for inflating the balloon. The plug may be pushed distally into position over the vent hole using a push rod inserted through the plug access hole.
The present invention also includes a method of using an intravascular occlusion balloon catheter having a removable hub in combination with a primary intravascular catheter having a guidewire lumen. In addition, the occlusion balloon catheter may have a venting mechanism, such that air may be vented from the balloon prior to intravascular insertion.